Henry Carrey Boston,MA . Carey/Kirzhner/Berestyaner , Belous , Isenberg - Lutsk ; Postolov/Herman/Kolovsky-Zhitomir
Most Libby's are named after a woman named Libe ( love or beloved ) pronounced "LEE-beh. sometimes shown as Liba . It is also possible that it could be Leah/Leye , but that is less likely .
Shirley is most often Sarah i.e Sore/Sure/Surke/Sorl/Surl etc. , but it could also be Sheyndl (SHEYN-dl ) from sheyn ( pretty or beautiful ) which also yields Sheyne /Shana/Shane/Shena in English . Shifre ( SHIF-reh ) is also possible.
As others have said , there are many possibilities, but the most common are Libe and Sore/Sure etc.
Henry H. Carrey